Format Converter with Smart Multitap and Upstream Signal Regulator

ABSTRACT

Systems and methods for signal conversion with smart multitap are disclosed. Embodiments of the systems can be scalable to model different signal topologies, transmission frequencies, bandwidths, and distances. An exemplary embodiment of the systems and methods includes a fiber optic to RF converter and a smart multitap. Although a fiber optic to RF converter is used in exemplary embodiments throughout the disclosure, conversion between other signal topologies is within the scope of the disclosure. The smart multitap includes a multiple tap for distributing a signal to multiple terminals and a microprocessor to select a particular terminal for a signal. Exemplary embodiments include downstream implementations in which a stream is typically sent from a service provider server to a user. Alternative embodiments include downstream implementations as well as upstream implementations in which a user typically sends a stream to a service provider server.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to co-pending U.S. utility patentapplication entitled “Format Converter with Smart Multitap” having Ser.No. ______ [Docket No.: A-9513; 191930-1850] which is filed on the sameday as, and with identical inventorship as, the present application.This application is also related to co-pending U.S. utility patentapplication entitled “Format Converter with Smart Multitap with DigitalForward and Reverse” having Ser. No. ______ [Docket No.: A-11312;191930-1750] which is filed on the same day as, and with identicalinventorship as, the present application. The related co-pending patentapplications listed above are hereby incorporated by reference in theirentirety into the present disclosure.

TECHNICAL FIELD

The present disclosure is generally related to data transmission and,more specifically to transmission of data to multiple terminals.

BACKGROUND

Electrical signals can be used for the transmission and distribution ofmedia signals, such as video and audio. The signals could incorporate,for example, analog and/or digital video, Moving Picture Experts Groupstreams (i.e. MPEG-1, MPEG-2, MPEG-4 (i.e. H.264)), Windows® Media(VC-1) streams, RealAudio streams, or MPEG Audio Layer-3 (mp3) streams,among others that can be used for the transmission of audio and/or videosignals in compressed digital streams. Accordingly, within the contextof this disclosure, a signal could comprise one or more of an audiostream, a video stream, or any other underlying media signals used toconvey information (text, graphics, animation, charts, graphs, etc.).

Such signals may be transmitted over a variety of distribution channelssuch as computer networks, satellite links, cable television (CATV)lines, radio-frequency signals, and digital subscriber lines (DSL),among others. A common medium used to transmit the signals is a fiberoptic cable. Fiber optic cables offer advantages in transmission speed,flexibility of the cables, and bundling of the cables with minimalcrosstalk issues, longevity, and upgradeability. However, since mostuser terminals cannot accept fiber optic signals, the fiber optic signalmay be converted to another format or topology, such as, a radiofrequency RF) signal. Another consideration for transmitting the signalsappears in multiple distribution point systems in high density areas.Having a system with a fiber optic to RF converter for each unit in ahigh density area can become exceedingly expensive. Accordingly, inlight of these potential deficiencies, among others, it is desirable toprovide a fiber optic to RF converter with a multi-tap capabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the drawings are not necessarily to scale relative toeach other. Like reference numerals designate corresponding partsthroughout several views.

FIG. 1 depicts an exemplary embodiment of a cable televisiondistribution network.

FIG. 2 is a schematic diagram of an exemplary embodiment of a downstream fiber optic to RF converter with a smart multitap used in thecable television distribution network of FIG. 1.

FIG. 3 is a schematic diagram of an exemplary embodiment of theconverter and smart tap of FIG. 2 with a burst mode gateway upstreamlink.

FIG. 4 is a schematic diagram of an exemplary embodiment of the fiberoptic to RF converter and smart multitap of FIG. 3 with a broadbanddigital reverse upstream link.

FIG. 5 is a schematic diagram of an exemplary embodiment of the fiberoptic to RF converter and smart multitap of FIG. 2 with digital forwardand reverse provided through an optical network terminal.

FIG. 6 is a flow diagram of an exemplary embodiment of a method fordownstream transmission using the system provided in FIG. 2.

FIG. 7 is a flow diagram of an exemplary embodiment of a method fordownstream and upstream transmission using the system provided in FIG.3.

FIG. 8 is a flow diagram of an exemplary embodiment of a method fordownstream and upstream transmission using the system provided in FIG.4.

FIG. 9 is a flow diagram of an exemplary embodiment of a method fordownstream and upstream transmission using the system provided in FIG.5.

DETAILED DESCRIPTION

Systems and methods for signal conversion with smart multitap aredisclosed. Embodiments of the systems can be scalable to model differentsignal topologies, transmission frequencies, bandwidths, and distances.An exemplary embodiment of the system includes a fiber optic to RFconverter and a smart multitap. Although a fiber to RF converter is usedin exemplary embodiments throughout the disclosure, conversion betweenother signal topologies is within the scope of the disclosure. The smartmultitap includes a multiple tap for distributing a signal to multipleterminals and a microprocessor to select a particular terminal for asignal. Exemplary embodiments include downstream implementations inwhich a stream is typically sent from a service provider server to auser. Alternative embodiments include downstream implementations as wellas upstream implementations in which a user typically sends a stream toa service provider server.

The described converter and smart multitap could be used in a number ofpotential electronic systems. FIG. 1 depicts an embodiment of oneparticular electronic system, a cable television distribution network100 in which embodiments of the converter and smart tap described hereinmay be used. In general, network 100 relays multimedia signals receivedfrom a number of sources, such as satellites 102, to a plurality ofremote locations 104. Such multimedia signals could be, for example,video and/or audio signals, which could also be transmitted withadditional network data, including Internet traffic, teletext, closedcaptioning, among others. The remote location 104 could be residences,educational facilities, or businesses that pay for, or otherwise receivecable television programming. Although reference may be made generallyto multimedia signals throughout the detailed description, signalshaving only one form of media, such as audio or video signals alone, areintended to be well within the scope of the disclosure. Some exemplaryembodiments provided herein allow multiple sources to have access to atransmission pipe to the home. This enables a user to select fromseveral different types of competing services.

Such multimedia signals and/or data signals may be transmitted overdownlink 106 from satellites 102 to respective receiver 108 at cablehead end 110. The signals received at cable head end 110 may bemultiplexed data streams. Such data streams may comprise compressedmultimedia streams transmitted in a variety of formats, such as, but notlimited to, MPEG 1, MPEG 2, MPEG 4, VC1, MP3, and/or RealAudio streams.Such compressed multimedia streams may be transmitted to cable head end110 at a variety of bit rates. The fiber to RF converter and smartmultitap may be located in the communication/transmission system 112 todistribute the stream to multiple units in a high density multipledwelling unit (MDU), for example. This decreases costs associated withdistributing the fiber signal to individual homes. If a fiber to RFconverter were necessary for each unit, the costs increase dramatically.The streams can be transmitted over communication connection 114 to oneor more converters at remote location 104. Communication connection 114may be, among others, a communications medium such as fiber optic cable,coaxial cable, telephone line, or wireless connection. Decoder 116 can,for example, decode and extract multimedia signals from the transmittedstreams for playback on playback device 118. Playback device 118 couldbe, for example, a television or audio playback system.

Decoder 116 could be, for example, in a cable television set top box.According to other embodiments, decoder 116 could be associated with atelevision, stereo system, or computing device (e.g., personal computer,laptop, personal digital assistant (PDA), etc.). Decoder 116 may receivea plurality of programs on a respective channel, each channel carried bya respective multimedia stream (which can include audio and videosignals, among others). Although the fiber to RF converter and smartmultitap may be described in certain embodiments as being included atthe MDU, the converter and smart tap could also be used in a number ofother locations, such as in head end 110 or in receiver 108, amongothers. For example, according to such an embodiment, receiver 108 mayreceive a signal in one format that is to be converted into a signal inanother format and then transmitted to multiple terminals within headend 110 or outside head end 110.

Now that a number of potential non-limiting environments have beendescribed in which the disclosed converter and smart multitap may beused, attention is now directed to various exemplary embodiments of suchconverter and smart multitap. It should be understood that any of themethods of processing described herein could be implemented in hardware,software, or any combination thereof. For example, when processing orprocess steps are implemented in software, it should be noted that suchsteps to perform processing could be stored on any computer-readablemedium for use by, or in connection with, any computer related system ormethod. In context of this document, the computer-readable medium is anelectronic, magnetic, optical, or other physical device or means thatcan contain or store a computer program for use by, or in connectionwith, a computer related system or method. The methods can be embodiedin any computer readable medium for use by, or in connection with, aninstruction execution system, apparatus, or device, such as a computerbased system, processor containing system, or other system that canfetch the instructions from the instruction execution system, apparatus,or device to execute the instructions.

In some embodiments, where the processing is implemented in hardware,the underlying methods can be implemented with any, or a combination of,the following technologies, which are each well-known in the art: (a)discrete logic circuit(s) having logic gates for implementing logicfunctions upon data signals, an application specific integrated circuit(ASIC) having appropriate combinational logic gates, (a) programmablegate array(s) (PGA), a field programmable gate array (FPGA), etc.; orcan be implemented with other technologies now known or later developed.

Any process descriptions, steps, or blocks in flow diagrams should beunderstood as potentially representing modules, segments, or portions ofcode which include one or more executable instructions for implementingspecific logical functions or steps in a process, and alternateimplementations are included within the scope of the preferredembodiments of the methods in which functions may be executed out oforder from what is shown or discussed, including substantiallyconcurrently, or in reverse order, depending on the functionalityinvolved, as would be understood by those reasonable skilled in the art.

FIG. 2 depicts an embodiment of fiber to RF converter and smart multitapsystem 200 that can be used at a business, educational facility, or MDU,in the cable head end 110 (or decoder 116, etc.) of FIG. 1. The fiber toRF converter and smart tap system 200 comprises fiber to RF converter202 and smart multitap 228. A fiber to multiple dwelling unit embodimentmay be utilized in a customer premise device for condominiums, apartmentcomplexes, and other high density areas. A normal fiber to the homeconnection with one home may comprise fiber to RF converter 202.However, using multiple converters 202 is expensive for a multipledwelling unit due to the increased number of fibers and fiber to RFconverters required to feed each individual unit at an MDU location. Thesmart tap shown includes four terminals, however, any number of tapscould be configured. For example, 4 taps, 8 taps, 12 taps, 16 taps, etc.

Fiber to RF converter 202 comprises fiber optic input 201 and RF output203. Photodiode 206 receives a signal from fiber optic input 201 whereit is then converted to an RF signal. The RF signal is conditioned foroutput in signal conditioning block 218, which includes bias stage 208,pre-amp stage 210, automatic gain control (AGC) stage 214, andinterstage-amp gain stage 216. The amplifier stages may comprisepush-pull amplifiers, linear amplifiers, digital amplifiers, or othermeans of amplification known now or later developed. The RF signal isbiased by bias network 208 and amplified in pre-amp stage 210. AGC isapplied at gain control stage 214 and the signal is again amplified atinterstage amp stage 216. Transformer 220 then takes the output ofpush-pull interstage amp 216 to generate the RF signal. Tilt stage 222applies a tilt to the signal, and output gain stage 224 applies a finalamplification to the signal where it is presented at RF output 203.

An advantage of using fiber optics follows from a constant level ofloss/frequency compared to different levels of loss/frequency for othermedia. For instance, in fiber optics, there is a single wavelength sentthrough the fiber. So losses occur, but the losses are constant becausethe signals are transmitted on a single wavelength. In a cabletelevision (CATV) system, each TV channel is transmitted on a differentfrequency. Channel 2 may be transmitted at 55.25 MHz, for example, whilechannel 110 may be transmitted at 745.25 MHz. For each channel in atypical CATV system, there may be 6 MHz between successive channels. So,for example, for a CATV system with one hundred and ten channels, thetotal bandwidth of the TV system is 6 multiplied by 110 channels addedto the frequency that the lowest channel is transmitted on plus anyoffset due to FM radio and over the air channel spacing. Through acoaxial cable, higher frequencies attenuate at a higher rate than lowerfrequencies. Therefore, a cable-shape loss occurs. Since the cable lookslike a low pass filter, as the signal travels down the coaxial cable, aloss occurs proportional to the length of the cable. When the signalpropagates through tilt stage 220 of converter 202, it is uptilted suchthat a higher frequency signal is attenuated less than a lower frequencysignal. Adding the uptilt from tilt 222 to the downtilt from the cableproduces a flat overall response. Tilt stage 220 counteracts for thecable loss. Tilt stage 220 may be implemented in one of many circuitsknown the art. Some gain is sacrificed in tilt stage 220 but the resultis a flat signal response.

Smart multitap 228 includes receiver 270, processor 272, splitters 230,232, 234, 236, 238, 240, and 242, switches 252, 254, 256, 258, 244, 246,248, 250, and terminals 260, 262, 264, and 266. Switch pairs 252 and244, 254 and 246, 256 and 248, and 258 and 250 may each be embodied in asingle switch. Receiver 270 includes a bandpass filter to filter acontrol signal from RF output 203. This control signal is tapped off ofRF output 203 at coupler 268. The control signal is then sent fromreceiver 270 to processor 272 to determine which of terminals 260, 262,264, and 266 should receive the RF signal. The RF signal progressesthrough splitter 230, which routes the RF signal into one of twodirections. One path goes to splitter 232 while the other path passesthrough filter 231 and then to splitter 238. Filter 231 may be used tofilter signals that individual customers have not subscribed to.

For example CATV systems have multiple levels of service; they may havea digital tier versus an all analog tier; they may have pay per view oreven digital internet traffic. Accordingly, filter 231 allows a systemoperator to remotely enable what services a customer receives. Fromsplitter 232 and 238 the RF signal proceeds through several splitters tocreate twice the number of feeds as terminals 260, 262, 264 and 266. Asingle RF feed from the non filtered side and a single feed from thefiltered side of splitter 230 emerge from the final set of splitters.Each RF feed, filtered and non-filtered, enters switches 252, 254, 256and 258. Each switch 252, 254, 256, 258 receives a command fromprocessor 272 directing it to either use the filtered or non-filtered RFfeed. The specific RF feed chosen by processor 272 emerges from thecommon port of the switches 252, 254, 256 and 258 and exits the multitapthrough terminals 260, 262, 264 and 266. Switches 252, 254, 256 and 258also may be terminated via the processor 272. This is useful for, amongother possibilities, disabling a customer who no longer lives in aresidence without having to send a technician to turn off the RF feed,or to test for ingress from specific locations that could be degradingsystem performance.

In one embodiment, the fiber to RF converter and smart multitapapplication uses multiple wavelength optical signals to accomplishtransmission of video, voice, and data. The receiver may compriseseveral stages, most of which can be implemented in different ways.Photodiode 206 can be a stand-alone photodiode if, for example, externalwavelength division multiplex components are used. In some embodiments,photodiode 206 may be enclosed in a diplexer or triplexer module whichmay include other wavelength division optical components.

Photodiode 206 may be biased in a number of ways. In an exemplaryembodiments, the biasing may be accomplished through transformer 208,which also may serve to improve receiver noise performance. Otheroptions include biasing photodiode 206 directly and using a highimpedance preamplifier stage such as preamplifier stage 210 to act asthe amplification and matching network for improved noise capability.Preamplifier stage 210 may match photodiode 206 to a lower outputimpedance. Pre-amp stage 210 and interstage amplifier stage 216 may beco-located into a single integrated circuit, or they may be separate.Interstage amp stage 216 may, for example, provide sufficient gain forsmart multitap 228 to drive a home network comprising a four-waysplitter and nominal system coaxial cable loss. The final outputimpedance of terminals 260, 262, 264, and 266 may be 75 ohms, which istypical for an in-home distribution network.

Amplifiers 210 and 216 of signal conditioning block 218 may be push-pullcircuits, but also could be single-ended stages, if their linearityperformance is sufficient. This could eliminate some transformers,thereby reducing costs. If the input noise performance of preamplifierstage 210 is low, cost may be reduced by eliminating an inputtransformer 208 and by biasing photodiode 206 through RF chokes.

Signal conditioning network 218 compensates for a potentially wide inputoptical power or for variations in the channel loading from head end110. An open loop compensation stage is incorporated to compensate for asignal derived from a sense line from photodiode 206. The optical inputpower is sensed, and a predetermined back-off is set to maintain anacceptable output signal level from terminals 260, 263, 264, and 266. Inthis way, installation may be simplified, as there is no need to set theoutput RF level. A 10 db variation in input optical power may result ina 20 db variation in RF level (prior to the gain control block 218),which is excessive for television 118 and set top terminal 116. Thepredetermined back-off approach is used if an optical modulation index(OMI) is known, and is constant.

A more sophisticated gain control option may include a linear gaincontrol circuit that is driven from an RF detection circuit. Thedetected level could be used in a closed loop automatic gain controlfunction, which would be useful if the OMI is not known. This gaincontrol circuit regulates the gain based on the power level it receivesfrom the RF detector to maintain a constant level at RF output 203.Since OMI can change as a function of channel loading, closed loopcontrol is more effective for systems that evolve over time. Thelocation of gain control circuit 214 is shown between pre-amplifierstage 210 and interstage amplifier stage 216, but could be placedbetween interstage amplifier stage 216 and output gain stage 224.Positioning gain control circuit 214 between input stage amplifier 210and interstage amplifier 216 may reduce the linearity requirements ofthe interstage and post amplifiers 216 and 224. However, it degrades thenoise performance and potentially adds costs due to the need foradditional transformers 220.

A less expensive automatic gain control approach involves limiting thegain variability to 0 db loss or 10 db loss. The threshold point can beadjusted to optimize noise performance, keeping RF output levels withinallowable limits. Adding hysteresis to the control circuitry mayeliminate an oscillatory state around the threshold point.

A feature of fiber optic to RF converter and smart multitap 200 is aconfigurable number of ports offered from one fiber optic line. Smartmultitap may provide non-limiting examples of 4, 8, 12, and 16-waycapabilities. The smart multitap is not limited to any number of portconfigurations. Converter and multitap 200 also provide several videoconditioning options, full service, tiered, and/or filter services, andthe capability to turn off individual ports. The filtered and off stateservices provide high insulation to prevent video theft.

Another feature of fiber to RF converter and smart multitap 200 isremote enabling capability. The service provider can control theservices provided through smart multitap 228. It could provide on (fullservice), tiered (through the use of the tiering filter capability ofthe smart multitap section), and off (disable the video) remotelythrough the network using a signal generated at head end 110 anddeciphered by control signal receiver 270 in smart multitap 228. Theenabling information is then sent to processor 272 which enablesswitches 252, 254, 256, and 258 in smart multitap 228 to select which ofterminals 260, 262, 264, and 266 is to receive the RF signal.

An alternative embodiment to the fiber to RF converter and smartmultitap is provided in FIG. 3. FIG. 3 depicts an embodiment of fiber toRF converter and smart multitap system 300 that can be used at abusiness, educational facility, or MDU, in the cable head end 110 (ordecoder 116, etc.) of FIG. 1. The fiber to RF converter and smart tapsystem 300 comprises fiber to RF converter 302 and smart multitap 328. Afiber to multiple dwelling unit embodiment may be utilized in a customerpremise device for condominiums, apartment complexes, and other highdensity areas. A normal fiber to the home connection with one home maycomprise fiber to RF converter 302. However, using multiple converters302 is expensive for a multiple dwelling unit due to the increasednumber of fibers and fiber to RF converters required to feed eachindividual unit at an MDU location. The smart tap shown includes fourterminals, however, any number of taps could be configured. For example,4 taps, 8 taps, 12 taps, 16 taps, etc.

Fiber to RF converter 302 comprises fiber optic input 301 and RF output303. Photodiode 306 receives a signal from fiber optic input 301 whereit is then converted to an RF signal. The RF signal is conditioned foroutput in signal conditioning block 318, which includes bias stage 308,pre-amp stage 310, automatic gain stage (AGC) stage 314, andinterstage-amp gain stage 316. The amplifier stages may comprisepush-pull amplifiers, linear amplifiers, digital amplifiers, or othermeans of amplification known now or later developed. The RF signal isbiased by bias network 308 and amplified in pre-amp stage 310. AGC isapplied at gain control stage 314 and the signal is again amplified atinterstage amp stage 316. Transformer 320 then takes the output ofpush-pull interstage amp 316 to generate the RF signal. Tilt stage 322applies a tilt to the signal, and output gain stage 324 applies a finalamplification to the signal where it is presented at RF output 303.

An advantage of using fiber optics follows from a constant level ofloss/frequency compared to different levels of loss/frequency for othermedia. For instance, in fiber optics, there's a single wavelength sentthrough the fiber. So losses occur, but the losses are constant becausethe signals are transmitted on a single wavelength. In a cabletelevision (CATV) system, each TV channel is transmitted on a differentfrequency. Channel 2 may be transmitted at 55.25 MHz, for example, whilechannel 110 may be transmitted at 745.25 MHz. For each channel in atypical CATV system, there may be 6 MHz between successive channels. So,for example, for a CATV system with one hundred and ten channels, thetotal bandwidth of the TV system is 6 multiplied by 110 channels addedto the frequency that the lowest channel is transmitted on plus anyoffset due to FM radio and over the air channel spacing. Through acoaxial cable, higher frequencies attenuate at a higher rate than lowerfrequencies. Therefore, a cable-shape loss occurs. Since the cable lookslike a low pass filter, as the signal travels down the coaxial cable, aloss occurs proportional to the length of the cable. When the signalpropagates through tilt stage 320 of converter 302, it is uptilted suchthat a higher frequency signal is attenuated less than a lower frequencysignal. Adding the uptilt from tilt 322 to the downtilt from the cableproduces a flat overall response. Tilt stage 320 counteracts for thecable loss. Tilt stage 320 may be implemented in one of many circuitsknown the art. Some gain is sacrificed in tilt stage 320 but the resultis a flat signal response.

Smart multitap 328 includes receiver 370, processor 372, splitters 330,332, 334, 336, 338, 340, and 342, switches 352, 354, 356, 358, 344, 346,348, 350, and terminals 360, 362, 364, and 366. Switch pairs 352 and344, 354 and 346, 356 and 348, and 358 and 350 may each be embodied in asingle switch. Receiver 370 includes a bandpass filter to filter acontrol signal from RF output 303. This control signal is tapped off ofRF output 303 at coupler 368. The control signal is then sent fromreceiver 370 to processor 372 to determine which of terminals 360, 362,364, and 366 should receive the RF signal. The RF signal progressesthrough splitter 330, which routes the RF signal into one of twodirections. One path goes to splitter 332 while the other path passesthrough filter 331 and then to splitter 338. Filter 331 may be used tofilter signals that individual customers have not subscribed to.

For example CATV systems have multiple levels of service; they may havea digital tier versus an all analog tier; they may have pay per view oreven digital internet traffic. Accordingly, filter 331 allows a systemoperator to remotely enable what services a customer receives. Fromsplitter 332 and 338 the RF signal proceeds through several splitters tocreate twice the number of feeds as terminals 360, 362, 364 and 366. Asingle RF feed from the non filtered side and a single feed from thefiltered side of splitter 330 emerge from the final set of splitters.Each RF feed, filtered and non-filtered, enters switches 352, 354, 356and 358. Each switch 352, 354, 356, 358 receives a command fromprocessor 372 directing it to either use the filtered or non-filtered RFfeed. The specific RF feed chosen by processor 372 emerges from thecommon port of the switches 352, 354, 356 and 358 and exits the multitapthrough terminals 360, 362, 364 and 366. Switches 352, 354, 356 and 358also may be terminated via the processor 372. This is useful for, amongother possibilities, disabling a customer who no longer lives in aresidence without having to send a technician to turn off the RF feed,or to test for ingress from specific locations that could be degradingsystem performance.

In one embodiment, the fiber to RF converter and smart multitapapplication uses multiple wavelength optical signals to accomplishtransmission of video, voice, and data. The receiver may compriseseveral stages, most of which can be implemented in different ways.Photodiode 306 can be a stand-alone photodiode if, for example, externalwavelength division multiplex components are used. In some embodiments,photodiode 306 may be enclosed in a diplexer or triplexer module whichmay include other wavelength division optical components.

Photodiode 306 may be biased in a number of ways. In an exemplaryembodiments, the biasing may be accomplished through transformer 308,which also may serve to improve receiver noise performance. Otheroptions include biasing photodiode 306 directly and using a highimpedance preamplifier stage such as preamplifier stage 310 to act asthe amplification and matching network for improved noise capability.Preamplifier stage 310 may match photodiode 306 to a lower outputimpedance. Pre-amp stage 310 and interstage amplifier stage 316 may beco-located into a single integrated circuit, or they may be separate.Interstage amp stage 316 may, for example, provide sufficient gain forsmart multitap 328 to drive a home network comprising a four-waysplitter and nominal system coaxial cable loss. The final outputimpedance of terminals 360, 362, 364, and 366 may be 75 ohms, which istypical for an in-home distribution network.

Amplifiers 310 and 316 of signal conditioning block 318 may be push-pullcircuits, but also could be single-ended stages, if their linearityperformance is sufficient. This could eliminate some transformers,thereby reducing costs. If the input noise performance of preamplifierstage 310 is low, cost may be reduced by eliminating an inputtransformer 308 and by biasing photodiode 306 through RF chokes.

Signal conditioning network 318 compensates for a potentially wide inputoptical power or for variations in the channel loading from head end110. An open loop compensation stage is incorporated to compensate for asignal derived from a sense line from photodiode 306. The optical inputpower is sensed, and a predetermined back-off is set to maintain anacceptable output signal level from terminals 360, 363, 364, and 366. Inthis way, installation may be simplified, as there is no need to set theoutput RF level. A 10 db variation in input optical power may result ina 20 db variation in RF level (prior to the gain control block 318),which is excessive for television 118 and set top terminal 116. Thepredetermined back-off approach is used if an optical modulation index(OMI) is known, and is constant.

A more sophisticated gain control option may include a linear gaincontrol circuit that is driven from an RF detection circuit. Thedetected level could be used in a closed loop automatic gain controlfunction, which would be useful if the OMI is not known. This gaincontrol circuit regulates the gain based on the power level it receivesfrom the RF detector to maintain a constant level at RF output 303.Since OMI can change as a function of channel loading, closed loopcontrol is more effective for systems that evolve over time. Thelocation of gain control circuit 314 is shown between pre-amplifierstage 310 and interstage amplifier stage 316, but could be placedbetween interstage amplifier stage 316 and output gain stage 324.Positioning gain control circuit 314 between input stage amplifier 310and interstage amplifier 316 may reduce the linearity requirements ofthe interstage and post amplifiers 316 and 324. However, it degrades thenoise performance and potentially adds costs due to the need foradditional transformers 320.

A less expensive automatic gain control approach involves limiting thegain variability to 0 db loss or 10 db loss. The threshold point can beadjusted to optimize noise performance, keeping RF output levels withinallowable limits. Adding hysteresis to the control circuitry mayeliminate an oscillatory state around the threshold point.

A feature of fiber optic to RF converter and smart multitap 300 is aconfigurable number of ports offered from one fiber optic line. Smartmultitap may provide non-limiting examples of 4, 8, 12, and 16-waycapabilities. The smart multitap is not limited to any number of portconfigurations. Converter and multitap 300 also provide several videoconditioning options, full service, tiered, and/or filter services, andthe capability to turn off individual ports. The filtered and off stateservices provide high insulation to prevent video theft.

Another feature of fiber to RF converter and smart multitap 300 isremote enabling capability. The service provider can control theservices provided through smart multitap 328. It could provide on (fullservice), tiered (through the use of the tiering filter capability ofthe smart multitap section), and off (disable the video) remotelythrough the network using a signal generated at head end 110 anddeciphered by control signal receiver 370 in smart multitap 328. Theenabling information is then sent to processor 372 which enablesswitches 352, 354, 356, and 358 in smart multitap 328 to select which ofterminals 360, 362, 364, and 366 is to receive the RF signal.

An alternative embodiment would include processor 372 being fed signalsfrom an alternate optical wavelength path that feeds an internal orexternal controller that would send the enabling information eitherdirectly to the switches or to processor 372 to control the switches asin the tap configuration of FIG. 3. This communication uses alternatewavelength signals present on the fiber, which provide a bidirectionaldigital signal path (used for data and voice communication, as well ascontrol functions). In addition, external controller switches may beprovided into the data stream providing full control of processor 372.

Diplex filter 374 allows the downstream signal from RF output 303through a high pass filter in diplex filter 374 down to signal splitter330. The low pass portion of diplex filter 374 also allows the upstreamsignal from the tap network to burst mode gateway 376 to be sent bylaser 378 onto the fiber optic cable. The burst mode gateway 376 maydisable the upstream transmission when it is not being used. When anupstream transmission is not being used, for example, in the middle ofthe night when upstream transmissions are infrequent, the burst modegateway 376 can turn off laser 378. Therefore, no additional bandwidthis being used by an upstream transmission and noise contributed by laser378 is reduced from the optical path. The fiber to RF converter andsmart multitap 300 contains a reverse path back to the headend in orderto provide interactivity which can be accomplished in many ways. In oneembodiment, a reverse gain block feeds a signal up a reverse paththrough the diplex filter 374 and burst mode gateway 376 to video ordigital laser 378 and uses a wavelength other than the one used by thedownstream converter as a single return path.

In an alternative embodiment, FIG. 4 depicts an embodiment of fiber toRF converter and smart multitap system 400 that can be used at abusiness, educational facility, or MDU, in the cable head end 110 (ordecoder 116, etc.) of FIG. 1. The fiber to RF converter and smart tapsystem 400 comprises fiber to RF converter 402 and smart multitap 428. Afiber to multiple dwelling unit embodiment may be utilized in a customerpremise device for condominiums, apartment complexes, and other highdensity areas. A normal fiber to the home connection with one home isjust fiber to RF converter 402. However, using multiple converters 402is expensive for a multiple dwelling unit due to the increased number offibers and fiber to RF converters required to feed each individual unitat an MDU location. The smart tap shown includes four terminals,however, any number of taps could be configured. For example, 4 taps, 8taps, 12 taps, 16 taps, etc.

Fiber to RF converter 402 comprises fiber optic input 401 and RF output403. Photodiode 406 receives a signal from fiber optic input 401 whereit is then converted to an RF signal. The RF signal is conditioned foroutput in signal conditioning block 418, which includes bias stage 408,pre-amp stage 410, automatic gain control (AGC) stage 414, andinterstage-amp gain stage 416. The amplifier stages may comprisepush-pull amplifiers, linear amplifiers, digital amplifiers, or othermeans of amplification known now or later developed. The RF signal isbiased by bias network 408 and amplified in pre-amp stage 410. AGC isapplied at gain control stage 414 and the signal is again amplified atinterstage amp stage 416. Transformer 420 then takes the output ofpush-pull interstage amp 416 to generate the RF signal. Tilt stage 422applies a tilt to the signal, and output gain stage 424 applies a finalamplification to the signal where it is presented at RF output 403.

An advantage of using fiber optics follows from a constant level ofloss/frequency compared to different levels of loss/frequency for othermedia. For instance, in fiber, there's a single wavelength sent throughthe filter. So losses occur, but the losses are constant because thesignals are transmitted on a single wavelength. In a cable television(CATV) system, each TV channel is transmitted on a different frequency.Channel 2 may be transmitted at 55.25 MHz, for example, while channel110 may be transmitted at 745.25 MHz. For each channel in a typical CATVsystem, there may be 6 MHz between successive channels. So, for example,for a CATV system with one hundred and ten channels, the total bandwidthof the TV system is 6 multiplied by 110 channels added to the frequencythat the lowest channel is transmitted on plus any offset due to FMradio and over the air channel spacing. Through a coaxial cable, higherfrequencies attenuate at a higher rate than lower frequencies.Therefore, a cable-shape loss occurs. Since the cable looks like a lowpass filter, as the signal travels down the coaxial cable, a loss occursproportional to the length of the cable. When the signal propagatesthrough tilt stage 420 of converter 402, it is uptilted such that ahigher frequency signal is attenuated less than a lower frequencysignal. Adding the uptilt from tilt 422 to the downtilt from the cableproduces a flat overall response. Tilt stage 420 counteracts for thecable loss. Tilt stage 420 may be implemented in one of many circuitsknown the art. Some gain is sacrificed in tilt stage 420 but the resultis a flat signal response.

Smart multitap 428 includes receiver 470, processor 472, splitters 430,432, 434, 436, 438, 440, and 442, switches 452, 454, 456, 458, 444, 446,448, 450, and terminals 460, 462, 464, and 466. Switch pairs 452 and444, 454 and 446, 456 and 448, and 458 and 450 may each be embodied in asingle switch. Receiver 470 includes a bandpass filter to filter acontrol signal from RF output 403. This control signal is tapped off ofRF output 403 at coupler 468. The control signal is then sent fromreceiver 470 to processor 472 to determine which of terminals 460, 462,464, and 466 should receive the RF signal. The RF signal progressesthrough splitter 430, which routes the RF signal into one of twodirections. One path goes to splitter 432 while the other path passesthrough filter 431 and then to splitter 438. Filter 431 may be used tofilter signals that individual customers have not subscribed to.

For example CATV systems have multiple levels of service; they may havea digital tier versus an all analog tier; they may have pay per view oreven digital internet traffic. Accordingly, filter 431 allows a systemoperator to remotely enable what services a customer receives. Fromsplitter 432 and 438 the RF signal proceeds through several splitters tocreate twice the number of feeds as terminals 460, 462, 464 and 466. Asingle RF feed from the non filtered side and a single feed from thefiltered side of splitter 430 emerge from the final set of splitters.Each RF feed, filtered and non-filtered, enters switches 452, 454, 456and 458. Each switch 452, 454, 456, 458 receives a command fromprocessor 472 directing it to either use the filtered or non-filtered RFfeed. The specific RF feed chosen by processor 472 emerges from thecommon port of the switches 452, 454, 456 and 458 and exits the multitapthrough terminals 460, 462, 464 and 466. Switches 452, 454, 456 and 458also may be terminated via the processor 472. This is useful for, amongother possibilities, disabling a customer who no longer lives in aresidence without having to send a technician to turn off the RF feed,or to test for ingress from specific locations that could be degradingsystem performance.

In one embodiment, the fiber to RF converter and smart multitapapplication uses multiple wavelength optical signals to accomplishtransmission of video, voice, and data. The receiver may compriseseveral stages, most of which can be implemented in different ways.Photodiode 406 can be a stand-alone photodiode if, for example, externalwavelength division multiplex components are used. In some embodiments,photodiode 406 may be enclosed in a diplexer or triplexer module whichmay include other wavelength division optical components.

Photodiode 406 may be biased in a number of ways. In an exemplaryembodiments, the biasing may be accomplished through transformer 408,which also may serve to improve receiver noise performance. Otheroptions include biasing photodiode 406 directly and using a highimpedance preamplifier stage such as preamplifier stage 410 to act asthe amplification and matching network for improved noise capability.Preamplifier stage 410 may match photodiode 406 to a lower outputimpedance. Pre-amp stage 410 and interstage amplifier stage 416 may beco-located into a single integrated circuit, or they may be separate.Interstage amp stage 416 may, for example, provide sufficient gain forsmart multitap 428 to drive a home network comprising a four-waysplitter and nominal system coaxial cable loss. The final outputimpedance of terminals 460, 462, 464, and 466 may be 75 ohms, which istypical for an in-home distribution network.

Amplifiers 410 and 416 of signal conditioning block 418 may be push-pullcircuits, but also could be single-ended stages, if their linearityperformance is sufficient. This could eliminate some transformers,thereby reducing costs. If the input noise performance of preamplifierstage 410 is low, cost may be reduced by eliminating an inputtransformer 408 and by biasing photodiode 406 through RF chokes.

Signal conditioning network 418 compensates for a potentially wide inputoptical power or for variations in the channel loading from head end110. An open loop compensation stage is incorporated to compensate for asignal derived from a sense line from photodiode 406. The optical inputpower is sensed, and a predetermined back-off is set to maintain anacceptable output signal level from terminals 460, 463, 464, and 466. Inthis way, installation may be simplified, as there is no need to set theoutput RF level. A 10 db variation in input optical power may result ina 20 db variation in RF level (prior to the gain control block 418),which is excessive for television 118 and set top terminal 116. Thepredetermined back-off approach is used if an optical modulation index(OMI) is known, and is constant.

A more sophisticated gain control option may include a linear gaincontrol circuit that is driven from an RF detection circuit. Thedetected level could be used in a closed loop automatic gain controlfunction, which would be useful if the OMI is not known. This gaincontrol circuit regulates the gain based on the power level it receivesfrom the RF detector to maintain a constant level at RF output 403.Since OMI can change as a function of channel loading, closed loopcontrol is more effective for systems that evolve over time. Thelocation of gain control circuit 414 is shown between pre-amplifierstage 410 and interstage amplifier stage 416, but could be placedbetween interstage amplifier stage 416 and output gain stage 424.Positioning gain control circuit 414 between input stage amplifier 410and interstage amplifier 416 may reduce the linearity requirements ofthe interstage and post amplifiers 416 and 424. However, it degrades thenoise performance and potentially adds costs due to the need foradditional transformers 420.

A less expensive automatic gain control approach involves limiting thegain variability to 0 db loss or 10 db loss. The threshold point can beadjusted to optimize noise performance, keeping RF output levels withinallowable limits. Adding hysteresis to the control circuitry mayeliminate an oscillatory state around the threshold point.

A feature of fiber optic to RF converter and smart multitap 400 is aconfigurable number of ports offered from one fiber optic line. Smartmultitap may provide non-limiting examples of 4, 8, 12, and 16-waycapabilities. The smart multitap is not limited to any number of portconfigurations. Converter and multitap 400 also provide several videoconditioning options, full service, tiered, and/or filter services, andthe capability to turn off individual ports. The filtered and off stateservices provide high insulation to prevent video theft.

Another feature of fiber to RF converter and smart multitap 400 isremote enabling capability. The service provider can control theservices provided through smart multitap 428. It could provide on (fullservice), tiered (through the use of the tiering filter capability ofthe smart multitap section), and off (disable the video) remotelythrough the network using a signal generated at head end 110 anddeciphered by control signal receiver 470 in smart multitap 428. Theenabling information is then sent to processor 472 which enablesswitches 452, 454, 456, and 458 in smart multitap 428 to select which ofterminals 460, 462, 464, and 466 is to receive the RF signal.

An alternative embodiment would include processor 472 being fed signalsfrom an alternate optical wavelength path that feeds an internal orexternal controller that would send the enabling information eitherdirectly to the switches or to processor 472 to control the switches asin the tap configuration of FIG. 4. This communication uses alternatewavelength signals present on the fiber, which provide a bidirectionaldigital signal path (used for data and voice communication, as well ascontrol functions). In addition, external controller switches may beprovided into the data stream providing full control of processor 472.

Broadband digital reverse (BDR) unit 476 digitally integrates theupstream transmission on a separate wavelength. The burst mode gatewayreverse does not transmit back upstream unless there is a signalpresent. For example, at three o'clock in the morning, when no consumeris occupying upstream bandwidth, the data stream is disabled so that ifanother customer is occupying bandwidth, they get more throughput. FIG.2 is an entirely downstream implementation. Commands can be sentdownstream and receiver 370 picks off the information from coupler 368.For the burst mode gateway, cost and reliability are of more concern.The technology is newer and has its own limitations.

BDR is something that most cable companies already use in the head end.The burst mode gateway would be used better in areas where there is ahigh concentration of ingress coming from interstates or industrialareas with propagation of noise problems. Also, the burst mode gatewayhas a limitation on a number of users. The more uses, the less viablethe technology. An advantage of the burst mode gateway includes turningoff its laser when signal is not present. With more users, thelikelihood of a use occupying bandwidth increases, reducing theeffectiveness of the burst mode gateway. The BDR digitizes the upstreamsignal and makes the upstream signal less susceptible to ingress, but itcontinues to run all the time whereas the burst mode gateway will shutdown the laser at certain times under certain conditions. Since thelifetime of the laser is based on its usage, that particular module maylast longer in the burst mode gateway embodiment.

In an alternative embodiment, FIG. 5 depicts an embodiment of fiber toRF converter and smart multitap system 500 that can be used at abusiness, educational facility, or MDU, in the cable head end 110 (ordecoder 116, etc.) of FIG. 1. The fiber to RF converter and smart tapsystem 500 comprises fiber to RF converter 502 and smart multitap 528. Afiber to multiple dwelling unit embodiment may be utilized in a customerpremise device for condominiums, apartment complexes, and other highdensity areas. A normal fiber to the home connection with one home maycomprise fiber to RF converter 502. However, using multiple converters502 is expensive for a multiple dwelling unit due to the increasednumber of fibers and fiber to RF converters required to feed eachindividual unit at an MDU location. The smart tap shown includes fourterminals, however, any number of taps could be configured. For example,4 taps, 8 taps, 12 taps, 16 taps, etc.

Fiber to RF converter 502 comprises fiber optic input 501 and RF output503. Photodiode 506 receives a signal from fiber optic input 501 whereit is then converted to an RF signal. The RF signal is conditioned foroutput in signal conditioning block 518, which includes bias stage 508,pre-amp stage 510, automatic gain control (AGC) stage 514, andinterstage-amp gain stage 516. The amplifier stages may comprisepush-pull amplifiers, linear amplifiers, digital amplifiers, or othermeans of amplification known now or later developed. The RF signal isbiased by bias network 508 and amplified in pre-amp stage 510. AGC isapplied at gain control stage 514 and the signal is again amplified atinterstage amp stage 516. Transformer 520 then takes the output ofpush-pull interstage amp 516 to generate the RF signal. Tilt stage 522applies a tilt to the signal, and output gain stage 524 applies a finalamplification to the signal where it is presented at RF output 503.

An advantage of using fiber optics follows from a constant level ofloss/frequency compared to different levels of loss/frequency for othermedia. For instance, in fiber optics, there's a single wavelength sentthrough. So losses occur, but the losses are constant because thesignals are transmitted on a single wavelength. In a cable television(CATV) system, each TV channel is transmitted on a different frequency.Channel 2 may be transmitted at 55.25 MHz, for example, while channel110 may be transmitted at 745.25 MHz. For each channel in a typical CATVsystem, there may be 6 MHz between successive channels. So, for example,for a CATV system with one hundred and ten channels, the total bandwidthof the TV system is 6 multiplied by 110 channels added to the frequencythat the lowest channel is transmitted on plus any offset due to FMradio and over the air channel spacing. Through a coaxial cable, higherfrequencies attenuate at a higher rate than lower frequencies.Therefore, a cable-shape loss occurs. Since the cable looks like a lowpass filter, as the signal travels down the coaxial cable, a loss occursproportional to the length of the cable. When the signal propagatesthrough tilt stage 520 of converter 502, it is uptilted such that ahigher frequency signal is attenuated less than a lower frequencysignal. Adding the uptilt from tilt 522 to the downtilt from the cableproduces a flat overall response. Tilt stage 520 counteracts for thecable loss. Tilt stage 520 may be implemented in one of many circuitsknown the art. Some gain is sacrificed in tilt stage 520 but the resultis a flat signal response.

Smart multitap 528 includes receiver 570, processor 572, splitters 530,532, 534, 536, 538, 540, and 542, switches 552, 554, 556, 558, 544, 546,548, 550, and terminals 560, 562, 564, and 566. Switch pairs 552 and544, 554 and 546, 556 and 548, and 558 and 550 may each be embodied in asingle switch. Receiver 570 includes a bandpass filter to filter acontrol signal from RF output 503. This control signal is tapped off ofRF output 503 at coupler 568. The control signal is then sent fromreceiver 570 to processor 572 to determine which of terminals 560, 562,564, and 566 should receive the RF signal. The RF signal progressesthrough splitter 530, which routes the RF signal into one of twodirections. One path goes to splitter 532 while the other path passesthrough filter 531 and then to splitter 538. Filter 531 may be used tofilter signals that individual customers have not subscribed to.

For example CATV systems have multiple levels of service; they may havea digital tier versus an all analog tier; they may have pay per view oreven digital internet traffic. Accordingly, filter 531 allows a systemoperator to remotely enable what services a customer receives. Fromsplitter 532 and 538 the RF signal proceeds through several splitters tocreate twice the number of feeds as terminals 560, 562, 564 and 566. Asingle RF feed from the non filtered side and a single feed from thefiltered side of splitter 530 emerge from the final set of splitters.Each RF feed, filtered and non-filtered, enters switches 552, 554, 556and 558. Each switch 552, 554, 556, 558 receives a command fromprocessor 572 directing it to either use the filtered or non-filtered RFfeed. The specific RF feed chosen by processor 572 emerges from thecommon port of the switches 552, 554, 556 and 558 and exits the multitapthrough terminals 560, 562, 564 and 566. Switches 552, 554, 556 and 558also may be terminated via the processor 572. This is useful for, amongother possibilities, disabling a customer who no longer lives in aresidence without having to send a technician to turn off the RF feed,or to test for ingress from specific locations that could be degradingsystem performance.

In one embodiment, the fiber to RF converter and smart multitapapplication uses multiple wavelength optical signals to accomplishtransmission of video, voice, and data. The receiver may compriseseveral stages, most of which can be implemented in different ways.Photodiode 506 can be a stand-alone photodiode if, for example, externalwavelength division multiplex components are used. In some embodiments,photodiode 506 may be enclosed in a diplexer or triplexer module whichmay include other wavelength division optical components.

Photodiode 506 may be biased in a number of ways. In an exemplaryembodiments, the biasing may be accomplished through transformer 508,which also may serve to improve receiver noise performance. Otheroptions include biasing photodiode 506 directly and using a highimpedance preamplifier stage such as preamplifier stage 510 to act asthe amplification and matching network for improved noise capability.Preamplifier stage 510 may match photodiode 506 to a lower outputimpedance. Pre-amp stage 510 and interstage amplifier stage 516 may beco-located into a single integrated circuit, or they may be separate.Interstage amp stage 516 may, for example, provide sufficient gain forsmart multitap 528 to drive a home network comprising a four-waysplitter and nominal system coaxial cable loss. The final outputimpedance of terminals 560, 562, 564, and 566 may be 75 ohms, which istypical for an in-home distribution network.

Amplifiers 510 and 516 of signal conditioning block 518 may be push-pullcircuits, but also could be single-ended stages, if their linearityperformance is sufficient. This could eliminate some transformers,thereby reducing costs. If the input noise performance of preamplifierstage 510 is low, cost may be reduced by eliminating an inputtransformer 508 and by biasing photodiode 506 through RF chokes.

Signal conditioning network 518 compensates for a potentially wide inputoptical power or for variations in the channel loading from head end110. An open loop compensation stage is incorporated to compensate for asignal derived from a sense line from photodiode 506. The optical inputpower is sensed, and a predetermined back-off is set to maintain anacceptable output signal level from terminals 560, 563, 564, and 566. Inthis way, installation may be simplified, as there is no need to set theoutput RF level. A 10 db variation in input optical power may result ina 20 db variation in RF level (prior to the gain control block 518),which is excessive for television 118 and set top terminal 116. Thepredetermined back-off approach is used if an optical modulation index(OMI) is known, and is constant.

A more sophisticated gain control option may include a linear gaincontrol circuit that is driven from an RF detection circuit. Thedetected level could be used in a closed loop automatic gain controlfunction, which would be useful if the OMI is not known. This gaincontrol circuit regulates the gain based on the power level it receivesfrom the RF detector to maintain a constant level at RF output 503.Since OMI can change as a function of channel loading, closed loopcontrol is more effective for systems that evolve over time. Thelocation of gain control circuit 514 is shown between pre-amplifierstage 510 and interstage amplifier stage 516, but could be placedbetween interstage amplifier stage 516 and output gain stage 524.Positioning gain control circuit 514 between input stage amplifier 510and interstage amplifier 516 may reduce the linearity requirements ofthe interstage and post amplifiers 516 and 524. However, it degrades thenoise performance and potentially adds costs due to the need foradditional transformers 520.

A less expensive automatic gain control approach involves limiting thegain variability to 0 db loss or 10 db loss. The threshold point can beadjusted to optimize noise performance, keeping RF output levels withinallowable limits. Adding hysteresis to the control circuitry mayeliminate an oscillatory state around the threshold point.

A feature of fiber optic to RF converter and smart multitap 500 is aconfigurable number of ports offered from one fiber optic line. Smartmultitap may provide non-limiting examples of 4, 8, 12, and 16-waycapabilities. The smart multitap is not limited to any number of portconfigurations. Converter and multitap 500 also provide several videoconditioning options, full service, tiered, and/or filter services, andthe capability to turn off individual ports. The filtered and off stateservices provide high insulation to prevent video theft.

Another feature of fiber to RF converter and smart multitap 500 isremote enabling capability. The service provider can control theservices provided through smart multitap 528. It could provide on (fullservice), tiered (through the use of the tiering filter capability ofthe smart multitap section), and off (disable the video) remotelythrough the network using a signal generated at head end 110 anddeciphered by control signal receiver 570 in smart multitap 528. Theenabling information is then sent to processor 572 which enablesswitches 552, 554, 556, and 558 in smart multitap 528 to select which ofterminals 560, 562, 564, and 566 is to receive the RF signal.

In FIG. 5, the downstream (forward), upstream (reverse), and digitaldownstream implementation is similar to fiber optic Ethernet capabilitywith video overlay. This could also be called the digital forward andreverse communication length with video overlay. This alternativeembodiment would include processor 572 for processing the digitalforward signals. The signals are detected on an alternate opticalwavelength path. The signals, which may include enabling and/or controlinformation, are provided either directly to the switches or toprocessor 572 to control the switches. This communication link usesalternate wavelength signals present on the fiber, which provides abidirectional digital signal path (used for data and voicecommunication, as well as control functions). In addition, externalcontroller switches may be provided into the data stream providing fullcontrol of processor 572.

Video overlay with forward and reverse digital capability allows formultiple vendors to provide competing services over the same fiber opticcable. This system configuration allows multiple vendors to split theinitial cost of the system. The advantage of this alternative embodimentis that a customer would have a choice of the standard CATV styleservices and/or digital upstream and digital downstream services thatpotentially have increased security and bandwidth. In this embodiment, auser may have an IP based network bypassing the traditional coaxialnetwork, using a standard Ethernet jack at terminal 590 where a user mayrouter and hub devices for the MDU location for processing and directingthe digital information. The digital information from the opticalnetwork termination (ONT) may be provided to a separate device thathandles a conversion to an IP-based or Ethernet-based protocol, asnon-limiting examples. This configuration is not unlike a digitalmodem/router with a video overlay.

In the embodiment of FIG. 5, the video overlay is provided to theterminals of the smart multitap; however, the optical digitalinformation may or may not. In triplexer 504, there are threewavelengths of light that are different wavelengths. Exemplarywavelengths include downstream video at 1550 nanometers, theupstream/reverse video/digital at 1310 nanometers and the digitalforward at 1490 nanometers. The digital reverse block 576 may alsohandle the optical network transmission upstream signal. The output ofthe optical network termination terminal 590 may also be communicativelycoupled to digital reverse block 576 to manage the upstream digitalsignal.

The flow diagram of FIG. 6 provides a method for downstream transmissionaccording to the system of FIG. 2. In block 600, a signal converterconverts a downstream signal from a first topology to a second topology.In an exemplary embodiment a fiber optic signal is converted to an RFsignal. In block 605, the downstream signal configured according to thesecond topology is distributed to multiple units through a smartmultitap. The particular terminal serviced with the multitap is selectedby a processor, which may receive instructions by means of a controlsignal, as a non-limiting embodiment. The control signal may bemodulated on the RF signal and received by a receiver, which demodulatesthe control signal for use by the processor.

The flow diagram of FIG. 7 provides a method for downstream and upstreamtransmission according to the system of FIG. 3. In block 610, upon thedirection of a user, an upstream signal is provided for transmissionfrom a unit through a smart multitap to a fiber optic transmissionlaser. In decision block 620, a determination is made as to whether anupstream transmission is present. In block 623, if an upstreamtransmission is present, it is propagated to the fiber optictransmission laser. In block 625, if no upstream transmission ispresent, the upstream transmission laser is disabled by means of a burstmode gateway. By turning off the fiber optic transmission laser, energyis saved, the reliability (proportional to use) of the fiber optictransmission laser is increased, and the bandwidth available forupstream transmission is increased.

The flow diagram of FIG. 8 provides a method for downstream and upstreamtransmission according to the system of FIG. 4. In block 630, upon thedirection of a user, an upstream signal is provided for transmissionfrom a unit through a smart multitap to a digital upstream transmitterusing broadband digital reverse technology to produce a digitalbroadband upstream signal. In block 635, the digital broadband upstreamsignal is applied to the fiber optic transmission laser.

The flow diagram of FIG. 9 provides a method for downstream and upstreamtransmission according to the system of FIG. 5. In block 640, adownstream signal with multiple signal components in at least a firsttopology is received. In block 645, a digital downstream component ofthe multiple signal components is forwarded to an optical networkterminal. In block 650, the video overlay component of the multiplecomponents of the downstream signal in the first signal topology isconverted to a second signal topology. In block 655, the resultant videooverlay component in the second topology is distributed to one or moreunits by means of a smart multitap. In block 660, upon direction of auser, an upstream signal from a unit is provided for transmissionthrough a terminal of the smart multitap or from the optical networkterminal. The upstream signal is provided to a digital upstreamtransmitter. In block 665, the digital broadband signal is transmitted.

The flow diagrams of FIGS. 6-9 show the architecture, functionality, andoperation software for implementing the converter and smart multitap ofFIGS. 2-5. In this regard, each block may represent a module, segment,or portion of code, which comprises one or more executable instructionsfor implementing the specified logical function(s). It should also benoted that in some alternative implementations, the functions noted inthe blocks may occur out of the order noted in FIGS. 6-9. For example,two blocks shown in succession may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved, as will be furtherclarified hereinbelow.

The software for implementing the converter and smart multitap of FIGS.2-5, which comprises an ordered listing of executable instructions forimplementing logical functions, can be embodied in any computer-readablemedium for use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions. In the context of this document, a“computer-readable medium” can be any means that can contain, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.The computer readable medium can be, for example but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or propagation medium. Morespecific examples (a nonexhaustive list) of the computer-readable mediumwould include the following: an electrical connection (electronic)having one or more wires, a portable computer diskette (magnetic), arandom access memory (RAM) (electronic), a read-only memory (ROM)(electronic), an erasable programmable read-only memory (EPROM or Flashmemory) (electronic), an optical fiber (optical), and a portable compactdisc read-only memory (CDROM) (optical). Note that the computer-readablemedium could even be paper or another suitable medium upon which theprogram is printed, as the program can be electronically captured, viafor instance optical scanning of the paper or other medium, thencompiled, interpreted or otherwise processed in a suitable manner ifnecessary, and then stored in a computer memory. In addition, the scopeof the present disclosure includes embodying the functionality of thepreferred embodiments of the present disclosure in logic embodied inhardware or software-configured mediums.

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments could include, while other embodiments do not include,certain features, elements and/or steps. Thus, such conditional languageis not generally intended to imply that features, elements and/or stepsare in any way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements and/or steps areincluded or are to be performed in any particular embodiment.

It should be emphasized that the above-described embodiments of thepresent disclosure, particularly, any “preferred” embodiments, aremerely possible examples of implementations, merely set forth for aclear understanding of the principles of the disclosure. Many variationsand modifications may be made to the above-described embodiment(s) ofthe disclosure without departing substantially from the spirit andprinciples of the disclosure. All such modifications and variations areintended to be included herein within the scope of this disclosure andthe present disclosure and protected by the following claims.

1. A system comprising: a module configured to convert a signal in afirst format to signal in a second format, the module including a firstdiplex filter; a configurable multitap for splitting the signal in thesecond format and selectively transceiving the signal in the secondformat through a plurality of terminals; a second diplex filter; and anupstream signal regulator electrically connected between the seconddiplex filter and the first diplex filter, the upstream signal regulatorconfigured to decrease the bandwidth requirements of an upstream signal.2. The system of claim 1, wherein the first format is capable of beingused over a fiber optic transmission medium.
 3. The system of claim 1,wherein the second format is capable of being used over a radiofrequency transmission medium.
 4. The system of claim 1, furthercomprising a processor for selecting at least one of the plurality ofterminals to receive the signal in the second format.
 5. The system ofclaim 4, further comprising a filter for passing a control signal to theprocessor.
 6. The system of claim 5, further comprising a demodulatorconfigured to demodulate the control signal for use by the processor. 7.The system of claim 5, wherein the filter is a bandpass filter.
 8. Thesystem of claim 4, wherein the configurable multitap comprises: aplurality of switches selectively controllable by the processor; and aplurality of splitters communicatively coupled to the plurality ofswitches.
 9. The system of claim 1, wherein the second diplex filtercomprises a high pass filter electrically connected to pass downstreamsignals between the module and the multitap.
 10. The system of claim 1,wherein the second diplex filter comprises a low pass filterelectrically connected to pass upstream signals between the multitap andthe first diplex filter.
 11. The system of claim 1, wherein the upstreamsignal regulator comprises a burst mode gateway.
 12. The system of claim1, wherein the upstream signal regulator comprises a module configuredto digitize the upstream signal.
 13. The system of claim 1, furthercomprising an upstream fiber optic transmission laser configured toapply the upstream signal to a fiber optic cable.
 14. The system ofclaim 13, wherein the upstream signal regulator comprises a burst modegateway.
 15. The system of claim 14, wherein the burst mode gatewaydisables the upstream fiber optic transmission laser if no upstreamsignal is present.
 16. The system of claim 13, wherein the upstreamsignal regulator comprises a module configured to digitize the upstreamsignal.
 17. A method comprising: receiving input from a user; providingan upstream signal corresponding to the input from the user fortransmission from the user through a terminal of a smart multitap to afiber optic transmission laser; determining if an upstream transmissionis present at the laser; propagating the upstream transmission to thelaser if an upstream transmission is present; and disabling the laserusing a burst mode gateway if no upstream transmission is detected. 18.A method comprising: receiving input from a user; providing an upstreamsignal corresponding to the input from the user for transmission fromthe user through a terminal of a smart multitap to a digital upstreamtransmitter by means of broadband digital reverse technology to producea digital broadband signal; and applying the digital broadband signal toa fiber optic transmission laser.
 19. The method of claim 18, whereinbroadband digital reverse digitizes the upstream signal.